Wireless audio communication systems typically employ an encoding scheme which is applied to a stream of audio data, for example to achieve compression, and then packetize the encoded data for transmission over a radio channel. During transmission, however, some packets can be lost or corrupted due to interference, fading, and other such problems. These invalid packets result in missing audio samples which cause audio glitches at the receiving end and negatively impact the user's listening experience. Packet loss concealment techniques are often employed to reduce this audio degradation. Packet loss concealment generally operates to provide replacement audio samples that approximate the missing audio samples caused by the invalid packet.
Many audio encoders/decoders (codecs) maintain state data during the encoding/decoding process. Such state data includes information related to the processing of previous audio samples and is necessary to correctly process the current and future audio samples. Unfortunately, when a missing, corrupted, or otherwise invalid packet is encountered, the decoder state data is lost and an output error will be introduced and propagated into the processing of subsequent valid packets. This error will generally cause a noticeable discontinuity (e.g., glitch) or phase distortion in the audio output despite any attempts at packet loss concealment.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent in light of this disclosure.